Download Various modifications of reverse sural artery flap

Study of various modifications of reverse sural artery flap
Introduction
Soft tissue reconstruction of distal third leg, heel and ankle region is a challenging problem
because of poor vascularity and limited mobility of skin. The reverse sural artery with ideal flap
thickness, minimal donor site morbidity, lack of functional muscle loss, short recovery time,
wide arc of rotation and safe vascularity makes it a preferable flap for covering such defects.
Aims ad objectives
To study various modifications of distally based reverse sural artery flap to suit the defects and
for better survival of flaps.
Results
It is a retrospective study conducted in our institute to cover the distal leg and foot defects.60
cases of distal leg defects exposing vital structure who underwent reverse sural artery flap
coverage were included in the study .5 of the 60 flaps had complete flap necrosis and another11
flaps had partial necrosis.73.4% of the flaps survived during the follow up period of 1 years with
good functional outcome.
Conclusions:
Reverse sural artery flap with its modifications is a good flap for the defects of distal leg, heel
and ankle defects
Key Words: Reverse sural artery flap, modifications, distal leg defects
MeSH terms-: Reverse sural artery flap, modifications, distal leg defects
INTRODUCTION
Soft tissue reconstruction of the lower third leg, ankle and foot region is a challenging
problem. The major problem is the poor vascularity and limited mobility of the skin. Tendon,
bone and hardware are frequently exposed because of the thinness of subcutaneous tissue
making possibility of skin grafting a poor option. A durable flap with good skin texture, reliable
vascularity, good arc of rotation, ease of dissection with minimum donar site morbidity is the
most desired option for covering such defects.
The different local flaps for hind foot defects including dorsalis artery flap 1,abductor hallucis
and abductor digiti minimi muscle flaps2,3 have inadequate tissue and limited arc of rotation
thereby limiting their frequent use. Medial plantar artery flap is an excellent option for weight
bearing heel but its involvement in trauma frequently precludes its use.
Locoregional flaps for lower leg and ankle defects such as the peroneal artery flap, anterior
tibial artery flap and posterior tibial artery flap 4-6 have the disadvantage of sacrificing a major
artery in already traumatised limb. Supramalleolar flap7 is another option but its reliabiality is
questionable in compromised vascularity.Morbidity and operative times are increased in
technically demanding microvascular surgeries8,9.Ideal flap thickness and quality, minimal
donor site morbidity, the lack of functional loss, short recovery time , the wide arc of rotation
and safe vascularity are the significant advantages of the reverse sural artery flap.
Masquelet et al10 . Introduced the sural flap in 1992 with concise description of relevant
anatomy and the surgical procedure. After the work of Masquelet et al distally based sural
fasciocutaneous flap has become a mainstay in the reconstruction of the the lower leg ,ankle
and heel defects. Over the past decade several modifications have been reported to improve
flap viability and to solve a myriad of reconstructive needs.
Material and methods
A total of 60 cases of lower limb defects over lower third tibia and foot that were treated with
distally based reverse sural artery flap in our institute over a period of 30 months from April
2011 to september 2013 constitutes the material of this study. The various modifications of the
flap included reverse sural island flap with either a subcutaneous tunnel or externally placed
pedicle, sural peninsular flap, sural fasciocutaneous flap, extended sural
fasciomusculocutaneous flap and delayed sural flap depending on the size and location of the
defect. The defects included post traumatic wounds exposing vital structures or hardware and
chronic nonhealing wounds requiring the flap cover. Chronic ulcers due to arterial and venous
insufficiency were excluded from the study.
Relevant Anatomy
The sural artery arises from the popliteal artery and joins the sural nerve coursing between the
two heads of gastronemius and follows the lateral edge of the Achilles tendon. The sural artery
is intimately connected with the sural nerve and plays an important role in supplying the skin of
lower and middle posterior leg. It terminates with the lateral supramalleolar branch of peroneal
artery. Approximately four to eight perforators arise from the peroneal artery, pierce the crural
fascia, and give rise to several branches that join adjacent perforators, forming an
interconnecting vascular suprafascial plexus that extends from proximal part of leg to the
posterior margin of lateral malleolus. A large perforator is located approximately 5cm proximal
to the lateral malleolus.
The lesser saphenous vein begins its course at the lateral border of the dorsum of foot, passes
below the lateral malleolus ,and travels along its posterior border. It then crosses the sural
nerve after travelling approximately 1/3rd of the length of the lower leg. More proximally, the
lesser saphenous vein is located between the heads of the gastronemius muscle.The lesser
saphenous vein remains superficial to the deep fascia until it passes through the popliteal fossa
to drain into the popliteal vein.
In most cases the sural nerve is formed by the union of the medial and the lateral sural
cutaneous nerve. The medial and lateral sural cutaneous nerves are branches of the tibial nerve
and common fibular nerve, respectively.
Surgical technique
Standard reverse sural island flap11
With patients in the prone position under general or spinal anesthesia the size of the defect is
measured and a cutaneous island to be transferred is marked out on the middle or distal third
of leg ,depending on the length of pedicle necessary to reach the wound.The pedicle is kept
centralised with regard to the flap. A line is marked from a point halfway between the Achilles
tendon and the lateral malleolus extending to the midline between the two heads of
gastronemius which roughly marks the course of the pedicle.
The pivot point is approximately 5cm proximal to the lateral malleolus and posterior to the
fibula.The axis of the pedicle is oblique and can be located precisely by the coarse of the lesser
saphenous vein . A reliable adipofascial pedicle should not exceed the ratio of 4:1.
The incision begins over the proximal border of the skin island and is carried down to the sub
fascial layer. The flap is elevated under tourniquet inflation. The sural nerve, and the
accompanying short saphenous vein are identified, ligated and cut.The flap is dissected from
proximal to distal, followed by the pedicle with an adjacent 1 to 2cm width of fascia. The fascia
must be included in both skin island and pedicle dissection.The viability of the flap is checked
after tourniquet deflation. Hemostasis ensured .The flap is transferred with the pedicle which
may be placed in a subcutaneous tunnel, open tunnel or externally placed with STG over it.
The secondary defect over donar site can be closed primarily when it is less than 4cm in
diameter . It should be covered with a partial thickness skin graft when it is larger.
Various modifications of reverse sural artery flap
1) Peninsular sural flap
Flap has a cutaneous artery and vein with overlying subcutaneous tissue and skin at its base.
The inclusion of skin over the pedicle is a useful modification because it facilitates better
manipulation of the flap and increases the margin of safety.
2) Sural artery fasciocutaneous flap12
The inferiorly based fasciocutaneous flap with sural artery incorporation , which is perfused by
peroneal perforators is an excellent modification and is more reliable. However disadvantage
of the modification includes lesser arc of rotation and larger donor defect.
3) Sural fasciomusculocutaneous flap13
The distally based sural fascio muculocutaneous flap, including a cuff of the gastronemius
muscle along with sural nerve , can preserve the retrograde blood supply from the median
superficial artery of the sural nerve to the musculocutaneous perforators of the gastronemius
muscle over this critical area.
4) Delayed sural flap14
Experience with delay procedure has established the safety and reliability of larger flaps
exceeding conventional flap dimensions in elderly patients with vascular risk factors. A delay
period of 10 days seems to be appropriate in reconstruction of traumatized extremities.
5) Supercharged reverse sural flap15
“Supercharging” means vascular augmentation of a flap by anastamosing the unrelated distant
vascular source of flap , while “turbojetting” involves anastamosing the vascular source already
present within the flaps pedicle to the flap.
6) Nerve sparing distally based sural fasciocutaneous flap 16
Distally based sural nerve flap causes an area of parasthesia over the lateral aspect of foot. To
prevent this the sural nerve was dissected from the vein by microdissection and this didnot
compromise the vascularity of the flap with preservation of sensation.
Results
Out of the 60 patients operated with reverse sural artery flap, 54 were male and 6 female patients
with age group ranging from 3 to 70 years. The etiology of the defects included posttraumatic,
post infective, post burn nonhealing ulcers and pressure ulcers over heel . 22 of the defects were
around the medial malleoli, 16 over the heel, 11 over anterior ankle and foot, 9 over the lower
1/3rd leg and 2 over lateral malleoli. There was an underlying bone, fracture , implant or tendon
exposed in all patients.43 of this patients underwent standard reverse sural island flap,10 reverse
sural fasciocutaneous flap, 3 delayed sural flap, 2 sural fasciomusculocutaneous flap and 2
peninsular sural flap .The size of the defects for island flaps ranged from 5x5cm to 9x8cm. The
length of sural fasciocutaneous flaps ranged from 7 to 25cm from the tip of lateral malleolus. 5
of these flaps underwent complete flap necrosis and 11 had partial necrosis which were later
covered with skin grafting after granulation.
Figure:1 Reverse sural island flap with externally placed pedicle
Figure:2 Reverse sural island flap. Secondary defect primarily closed
Figure:3 Sural island flap with subcutaneous tunneling of pedicle
Figure:4
Sural artery peninsular flap
Figure:5 Reverse Sural artery fasciocutaneous flap
Figure:6 Delayed reverse sural artery flap
Figure:7 Extended sural fasciomusculocutaneous flap
Discussion
Reverse sural artery flap remains the workhorse flap for reconstruction of foot and ankle
defects.The constant and reliable blood supply with ease of elevation makes it a preferable
flap for this defects. The various modifications of the flap are done to suit clinical conditions
and for better survival of the flap. Distal sural artery flap can be used to cover defects over
medial and lateral malleoli, over dorsum of foot and ankle and weight bearing heel. Flap is safe
in paediatric age group, with no difference in complication rates. Inclusion of both the
accompanying vascular territories of the sural nerve as the main arterial supply and the lesser
saphenous vein as an additional blood supply and to augment the venous drainage of the flap
improves survival. Inclusion of skin over the pedicle as in peninsular and fasciocutaneous flaps
facilitates better manipulation of the flap and increases margin of safety. Flap can be safely
elevated from proximal 1/3rd of leg by inclusion of mesentry like tissue between gastronemius
muscles or a chunk of gastronemius muscle itself. Delay flap is preferred in high risk patients
with diabetes, smoking and hypertension. The long pedicle sural artery fasciocutaneous flap is
preferred in patients who have large defects over the weight bearing heel and over foot.
Large donar site deformity was the disadvantage with long pedicle fasciocutaneous flap but
with the advantage of better survival. Flap edema and venous congestion were the most
common complications in immediate post operative period, which settled with no serious
problems. Loss of sensation over the lateral aspect of foot was a common but not a major
complaint in late follow up.
Conclussion
The distally based reverse artery flap with its various modifications is an ideal flap for covering
defects over distal 1/3rd leg, ankle and proximal foot defects.
References
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